Slip-ring units usually include two component groups, e.g., a stator and a rotor. The stator often includes brushes, whereas the rotor usually has a succession of slip rings. During operation, the brushes have sliding contact with rotating slip rings along what are referred to as tracks. Such slip-ring units are used in many technical fields to transmit electrical signals or electric power from a stationary unit to a rotating electrical unit.
For example, such slip-ring units are incorporated in the rotor hub or the nacelle of wind power plants to transmit control signals, for example, and/or electric currents for drives in order to adjust the angle of attack of the rotor blades.
It is especially important in the case of such high-grade plants or machines that their availability not be reduced by the slip-ring unit.
U.S. Pat. No. 6,034,531 describes a system for monitoring the wear of a rubbing electrical contact for heating the rotor blades of a helicopter.